This invention relates in general to mold bases for plastic molding materials and more particularly to a design which is adapted to employ tungsten carbide mold cavities thereby reducing the wear on the mold cavity when glass and asbestos fiber and particle filled molding materials are used.
The abrasiveness of many reinforced molding compounds, and in particular glass-fiber filled and asbestos-fiber filled molding compounds, creates a great deal of wear on the mold cavity pieces. This wear results in excessive and costly replacement of the cavity pieces and much equipment downtime.
Accordingly, it is a major purpose of this invention to provide a mold base design which will operate for extended periods of time without requiring replacement of the mold cavaties when abrasive molding materials are employed.
The material tungsten carbide is known to be a very wear-resistance material. It is extremely hard and can withstand the very high pressures to which mold cavity pieces are subjected. However, tungsten carbide is a very brittle material and as a practical matter, it cannot be used in most, if not all, known plastic mold bases because of its tendency to crack and shatter.
Accordingly, another purpose of this invention is to provide a mold design and base which can accommodate to the use of tungsten carbide mold cavity pieces with minimum risk of the tungsten carbide pieces cracking or shattering during use.
Consistent with the above purposes, it is a further purpose of this invention to provide a mold base which will minimize maintenance and repair problems.